Mechanical oscillator



Aug. 30, 1938. NUNN 2,128,314

MECHANICAL OSC ILLATOR Filed July 2, 1937 3 Sheet-Sheet 1 Aug. 30, 1938.

E. D. NUNN 2,128,314

MECHANICAL OSCILLATOR Filed July- 2, 1937 5 Sheets-Sheet 2 53 m %2/e7z/07 Z fizz/27a.

Aug. 30, 1938. E. D. NUNN MECHANI CAL OSC ILLATOR Filed July 2, 1957 Z'yd 3 Sheets-Sheet 3 [Away Wm W Patented Aug. 30, 1938 UNITED STATES PATENT OFFICE 10 Claims.

This invention relates to a mechanical oscillator and, more particularly to one adapted to control one or more electric circuits. In certain cases such as road signs, electric fences and 5 other systems, a predetermined intermittent control of an electric circuit is desirable. of Oscillation in such devices is generally very long, of the order of one or more seconds. It is desirable that the electric circuits supply the energy losses of the oscillating system and to this end it is advantageous to make the conversion from electricity to mechanical energy as efiiciently and as simply as possible. Because such devices may be disposed in places that are not readily accessible to service, it is necessary that the entire device be as trouble-proof and as simple as possible. It is also highly desirable that the device function in any position whatever without substantial effect on its operation and e also operate at a uniformly high level of efficiency over wide variations of voltage in the supply circuit. Inasmuch as such devices involve contacts which open and close, it is necessary that sticking of contacts be eliminated and a 25 mechanical wiping action be provided which will maintain the contacts in a clean condition during the operation of the device.

Referring to the drawings: Figure 1 shows a plan view of the device with 30 the cover removed.

Figure 2 is a sectional view on line 2-2 of Figure 1.

Figure 3 is a sectional view on line 3-3 of Figure 1.

35 Figure 4 is a sectional detail on line 4-4 of Figure 3.

Figure 5 is a view partly in section of the mechanical portions of the oscillating system.

I Figure 6 is a front view similar to Figure 1 40 and partly in section showing the mechanical,

oscillator in an off-normal position.

Figure 7 is a circuit diagram of the system. A metal sub-base 10 has insulatingly mounted thereon by bolts H and I2 a transformer I5. It 45 is understood, of course, that an ordinary electromagnet may be used in place of the transformer if simplification of the system is desired.

Transformer l5 has a primary winding l6 and a secondary winding l'l suitably disposed over a laminated core I3 having a general shape of an E. The core is preferably provided with they usual edge covering or rim and the entire stack is maintained by bolts 2! and 22. Edge covering or rim 20 of the transformer core is pro- 56 vided with a lip 23 from one end thereof and this The period is bent to lie substantially in line with the free ends of the core legs.

Carried by lip 23 in any suitable fashion such. as, for example, by means of a screw and nut 24 is a leaf spring 25 to which is riveted an armature 5 26 extending across the free ends of the E shaped core. Spring 25 is normally so adjusted as to bias armature 26 away from the core.

Disposed on the free end of armature. 26 is a stack including a finger 21 carrying a contact 28 at the end thereof. An insulating strip 30 is disposed along the back of finger 21. A plurality of spacing members 3| are disposed along the outside of strip 30. A stop finger is dipsosed in the stack and extends toward the pivotal end of the armature to normally engage the free end of a bolt 36 adjustably disposed in a post 31 carried by sub-base III. A spring buffer member 38 is disposed at the outer end of the stack and has the free end thereof 39 bent as shown. A contact 40 is mounted on bent end 39. The entire stack is maintained intact by a bolt 4| passing through the various strips. An insulating bushing 42 may be provided around the bolt to insulate the various contact carrying members from each other and from the armature.

As is evident from Figure 4, metallic contact between armature 26 and finger 21 provides a through circuit. Also a metallic connection between fingers 35 and 38 provides a through circuit from bolt 36 through to contact 40. This contact 40 may be connected to any suitable means for indicating purposes. It is understood, of course, that various changes may be made to obtain different connections as may be found desirable.

Extending upwardly from sub-base III are a pair of posts 45 and 46 disposed near the opposite edges of the base. These posts are preferably of equal height and carry a yoke 41 in spaced relation to the sub-base proper. At'an intermediate point on the yoke 41 a shaft 50 is mounted and extends down through sub-base ID. The ends of the shaft are flattened down at 5| and 52 to provide retaining heads. This shaft provides a fixed surface around which the mechanical oscillating system moves.

In order to provide a smooth running and as near frictionless surface as possible and one which will withstand shocks and yet be easy and cheap, the following construction is provided. Disposed around shaft 50 adjacent sub-base I0 is a small metal collar 53. Collar 53 is adapted to abut against the outside surface of sub-base i0 and has grouped around the other end a series to move together.

of ball-bearings 54. A metal sleeve 55 which is normally free of shaft 50 has recesses cut out at the ends 56 and 51. End 56 of the sleeve encloses ball-bearings 54. End 51 of sleeve 55 is similarly provided with a series of ball-bearings 60 and a small metal collar 6!. n the other side of collar 6| are additional ball-bearings 62 all surrounded by a sleeve 63 similar'to sleeve 55 and having recesses 64 cut out therein. Ball bearings 65 are disposed at the other end of sleeve 63 and a collar 66 disposed around shaft 50 abuts against the yoke 41. In effect, the entire assembly comprises a pair of independently revoluble sleeves mounted on ball-bearings and lotatable around fixed shaft 50.

Sleeve 55 carries at one end 56 a pair of arms 68 and 69 rigidly fastened thereto. Arm 68 is preferably shorter than arm 69 for a purpose which will be apparent later and both of these arms are provided with weights "Ill and l I. Sleeve 63 is similarly provided with arms 12 and 13 and weights l4 and 15. Weight H is provided with a pin 16 which extends out far enough to engage the side of weight 15. Arms 68 and 12 may be equal and the same may be true of arms 69 and 13. Weights I0 and H, together with. pin 16, are so proportioned that the center of oscillation of the entire system is located at the center of shaft 50. The same is true of weights 14 and 15.

Disposed around sleeve 55 is a coil spring 18 having its end 19 (Figure 3) hooked around arm 68 while its other end is hooked to engage arm 12. Around sleeve 63 a coil spring 82 is disposed whose end 83 engages arm 13 while the other end engages yoke 41.

As is evident in Figures 1 and 3, weights 10 and 14 clear extending arms 21 and 38 carried by pivoted armature 26. Weight 15, however, extends far enough to engage the ends of arms 21 and 38. Weight 15 carries a pair of contact points 85 and 86 on opposite faces thereof. Contact point 86 is adapted to cooperate with contact point 28, while contact point 85 is adapted to cooperate with contact point 4|].

As is clear from Figure 5, the mechanical oscillation system is composed of two sections, each one having its own mass and elastic elements. In the normal movement of the system, the limits .of amplitude of weights l0 and H is determined by contacts 28 and 4|]. Between these limits, pin 16 connecting the two sections causes them It should be noted, however, that during this simultaneous movement, only spring 82 has energy stored therein since there is no relative motion between the two sets of weight arms.

It is obvious, however, that the system of weights I4 and 15 may move independently of the weights l0 and H to provide an excess amplitude of travel of almost an entire revolution, the angle subtended by pin 16 being the sole difference. Upon such additional movement of weights 14 and 15, it is clear that both sections of. the spring will be utilized to store energy. Hence, at moderate amplitude, when both systems of weights move together, the mass of the oscillating system is at a maximum, while the elasticity is represented by one spring section. Excess amplitude, when the two systems of weights are independent, utilizes but two of the weights and both springs. This, of course, would make the resonant frequency of the excess amplitude substantially higher than the resonant frequency of the two sections at moderate amplitudes. By suitable proportion of weights and springs, it is possible to design the oscillatory system so that a substantially constant resonant frequency for the entire system, as measured by the operation of contacts 28 and 85, is obtained within wide limits of energy input.

Carried by bolts 81 and 88 on sub-base III is a small U shaped permanent magnet 90, the poles of which are so disposed as to just clear the sides of weight H. Weight H is preferably made of iron and is so adjusted that the maximum attractive force from the magnet is exerted in the position of the device shown in Figure 1 wherein contacts 28 and 88 are tightly pressed against each other.

A condenser 92 is connected across contacts 28 and 86 but having one end 93 grounded to base l0 and the other end connected to armature 26 at bolt 25.

Disposed in the secondary circuit of the transformer, merely as an example of a signal-indicating device or as a load, is a lamp base-96 carrying a lamp 91. A toggle switch I0!) is provided for controlling the transformer primary circuit. Both the lamp base and toggle switch are preferably mounted in a metal cover plate lfll having a dished shape. The entire apparatus itself, carried on sub-base I0 is insulatingly mounted on rubber bumpers )3 to a dished member )4, similar in shape to IDI. The flanged edges I and I06 of the two plates may be provided with a sealing gasket I01 disposed therebetween and the two plates bolted together to enclose the entire mechanism.

When the transformer primary circuit is energized, the armature 26 will be attracted toward the transformer core, since contacts 28 and '86 are normally closed in the rest position of the device as shown in Figure 1. In pulling the armature over against the transformer core, contact 28 will push contact 86 in front of it and cause weights 14 and 15 to be moved initially in an anti-clockwise direction as seen in Figure 1. At the same time pin 16 carried by lower weight ll bears against upper weight 15 and causes both weights and H to move with upper weights l4 and 15. In this initial swing, spring 82 alone is wound up. Obviously, while both systems of weights are moving together there is no storage of energy in the lower spring 18 since both ends thereof are moved together in the same direction with reference to the stationary point 50. The extent of this initial anti-clockwise impulse will depend upon the intensity of the pull on the armature. In general, however, this first initial anti-clockwise swing will be less than 180 degrees. Obviously, when the weights reach the end or the firstswing, the tendency of lower spring 82 to unwind will cause upper weights 14 and to begin to go back to the original starting position. Again pin 16 extending up to weight 15 will connect two systems together and in this case the weights 10 and II will be forced to follow the upper weights l4 and 15. At the completion of the reactionary swing, contacts 28 and 86 will close again, thus energizing the transformer again. .The shock of closure is taken up by spring finger 35 bearing against screw 36. Upon the ill second excitation of the transformer'pn'mary, a

40 (see Fig. 6) then upper weights l4 and 15 will swing with lower weights 10 and II with a resultant interchange of energy with spring 82 only. If, however, the current in the primary of the transformer is sufilciently great by reason of overvoltage or the like, it is possible that a large amount of mechanical energy will be imparted to the armature 26 at periodic intervals. Under those conditions, and after the amplitude of vibration has attained its maximum value, it is clear that weight 15 may swing around anticlockwiseas seen in Figure 1 so far as to strike contact 48 with substantial force. In that event the momentum'of bottom weights i8 and "II will cause these weights to continue further in their anti-clockwise direction (see Fig. 6) and store energy in lower spring 18 as well as upper spring 82. This is because there is relative motion between the lower system of weights and the upper system of weights. Spring 82 will also be wound up additionally since weights l4 and 75 are moving with respect to the fixed point 50. When weights in and H have reached their limit of travel, they stop and begin to reverse their movement; In the meantime, upper weights M and '85 are maintained in their extreme position with contacts ll] and 85 closed by virtue of spring 18 as shown in Fig. 6. Upon the return motion of lower weights l8 and ii pin it; will be engaged by upper weight 5 at the proper point and pull weights M and. 15 back with them in their clockwise motion.

By this compound action, I have energized the transformer primary with currents at from 2 volts to 7 volts while maintaining a substantially constant frequency of contact interruption between driving contacts 28 and 86. This,

of course, would mean that any signal means controlled 'by the transformer secondary would be operated at substantially constant frequency.

During this range of operation, the amplitude of the oscillating system varied from an angle smaller than that required to bring contact 85 around to contact 48, in other words, with the two sys-' temsof weights working together, up to a value Where contacts 40 and 85 were closed and wherein. the lower weights H and 10 swung around by themselves. It is clear that if the lower weights swing around enough, that pin 16 will be carried around and strike upper weight I on the reverse side tending to drive upper weight 15 and its contacts 85 against contact 40. The shock of contacts 48 and 85 closing are taken up by the movement of armature 28 toward the transformer core against its spring bias.

By adjusting the electrical overloading of the transformer primary, it is possible to control the excess amplitude of the system and thus control the duration of time when contacts 86 and 40 are closed.

The magnet is effective only when contacts 28 and 85. are closed or nearly closed and at other times has practically no effect. This is desirable since it provides additional contact pressure without in any way, limiting the adjustability of the springs of the oscillating system.

Obviously, the various weights may'be adjusted as to size and distance so that the period of vibration of the entire device may be varied within limits.

What is claimed is:

1. A mechanical oscillator comprising a plurality of weights and a plurality of springs oscillatable about an axis and cooperating with each other to transform kinetic energy'into potential energy and back again, means for imparting energy impulses to one weight for oscillatory purposes, means for coupling all weights to oscillate as a unit for a predetermined amplitude, means for coupling one spring to said coupled weights to obtain an oscillating system, and means only operative above a predetermined amplitude for limiting one weight to said predetermined amplitude and permitting the remaining weights to travel above said amplitude and at the same time coupling all springs to said remaining weights whereby a composite oscillator having a substantially constant natural period over wide ranges of amplitude is obtained.

2. A mechanical oscillator comprising two 05- the mass elements of one system to maintain continuous oscillations, means for coupling said two systems together to oscillate as a unit over a predetermined amplitude, means whereby one spring only is coupled to said two weights during the simultaneous oscillations, means for limiting the weight of the first system to said predetermined amplitude, means for limiting the oscillations of the weight of said second system to another and greater predetermined amplitude and means operative only during said excess amplitude for coupling said two springs to the one weight.

3. An electromagnetic oscillator comprising a pair of superposed arms, each having weights and each independently oscillatable about a fixed axis, spring members associated with each pair of arms, an electric contact movable with one of said weights, an electromagnet having a vibratable armature, a contact carried by said armature and adapted to cooperate with said first contact for completing an electromagnetic circuit and feeding mechanical impulses to said one weight, means for limiting the amplitude of said system containing said one weight, means for coupling said two systems of weights for simultaneous oscillations over said predetermined amplitude and means whereby said other system of weights may oscillate independently at amplitudes beyond said predetermined amplitude.

4. A control switch comprising an oscillating member having mass and elasticity and adapted to oscillate between two end positions, a plurality of electric contacts, means for closing said contacts at the end positions of said oscillating means and maintaining said contacts open at intermediate positions, means for transmitting periodic mechanical impulses to said oscillating means for maintaining continuous oscillations and additional oscillating means having a permissible amplitude greater than said first named oscillating means and adapted to oscillate with said first named oscillating means and to oscillate independently over the excess amplitude.

5. The structure of claim 4 wherein the mechanical impulses to said oscillating system are fed entirely through certain of said contacts.

6. An electric switch comprising an electromagnet having a movable armature normally biased away therefrom. a contact movable with said armature and controlling the magnet circuit,

an oscillation system comprising two superposed units, each unit having weights and springs, a contact movable with one unit, means for limiting the amplitude of said one unit to less than 360 degrees, means for limiting the amplitude of said second unit to less than 720 degrees, means for coupling said two units together for oscillations within the lower amplitude limits, and means only operative in the closed position of the contacts for biasing the oscillation units to increase the contact pressure.

7. An electric switch comprising an electromagnet having a movable armature normally biased away therefrom, a contact movable with said armature for controlling said magnet circuit, a pair of superposed oscillation units, each comprising a pair of arms carrying weight elements, a spring between the arms of one unit and a fixed point on the apparatus, a spring between the arms of one unit and the arms of the other unit, said springs cooperating with said weights, to determine periods of oscillation, a contact movable with said one oscillation unit, means for moving said second oscillation unit with said first unit over a predetermined amplitude, means for limiting the movement of said one oscillation unit to said predetermined amplitude, means for limiting the movement of the other unit to a greater predetermined amplitude, said other unit being adapted to move alone at amplitudes in excess of said lower amplitude.

8. The structure of claim 7 wherein additional contacts are provided and adapted to be closed by the movement of said one unit when said unit is at the limit of its travel and preparatory to said other unit moving forward alone.

9. The structure of claim 7 wherein a permanent magnet is provided and adapted to cooperate with a weight element of the other unit only during the time when the impelling contacts are closed.

10. In a device of the character described, a plurality of counterbalanced weighted arms rotatably mounted about an axis, spring means for biasing each pair of counterbalanced arms to a predetermined position, means for mechanically coupling said arms for simultaneous rotation only above a predetermined amplitude and electromagnetic means for maintaining one of said counterbalanced arms in continuous oscillations.

EWING D. NUNN. 

